As a conventional motor for an electric power steering device, there is known one in which a frame that contains a rotor is formed with a bearing concave portion for non-rotatably and axially movably containing an outer ring of a bearing that rotatably supports a shaft of the rotor, a wave washer is made to intervene between the bearing concave portion and the bearing, and a preload is applied to the outer ring of the bearing with the wave washer; and accordingly, vibration resistance is improved.
[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-359945